plasticity + functional recovery

• plasticity:

  • brains tendency to adapt and change as a result of experience and learning
• plasticity over life:

  • during infancy - brain experiences rapid growth in lots of synaptic connections
  • as we age - rarely used connections deleted and frequently used connections strengthened (pruning)
• maguire et al -

  • london taxi drivers - higher volume of grey matter in posterior hippocampus than control group - part of brain associated with spatial + navigation skills
  • training - drivers complete 'the knowledge'
  • longer length of job = more pronounced structural difference
• draganski et al:

  • brain scans of medical students 3 months before exam and after
  • learning induced changes can be seen in posterior hippocampus and parietal cortex
• kuhn et al:

  • compared control group to video game training group who played super mario for at least 30 mins a day
  • increase in grey matter in hippocampus and cerebellum
• functional recovery:

  • after damage from trauma - brain has ability to redistribute or transfer functions performed by damaged to undamaged areas
  • neuroscientists say process occurs quickly after trauma (spontaneous recovery) + slows down after several weeks/months
  • may require rehab therapy for further recovery
• brain during recovery:

  • rewire and reorganise itself by forming new synaptic connections close to damaged area
  • secondary neural pathways -not typically used to carry out functions, are activated and unmasked to allow functioning to continue
• structural changes in brain:

  • axonal sprouting
  • denervation supersensitivity
  • recruitment of homologous areas
• axonal sprouting:

  • growth of new nerve endings - connect other undamaged nerves cells to create new neural pathways
• denervation supersensitivity:

  • axons that do a similar job are aroused to higher level to compensate for ones lost
• recruitment of homologous areas:

  • specific tasks carried out by equivalent part in other hemisphere
  • e.g damage to broca's area results in same area of right hemisphere carrying out functions - after time functionality may switch back to left
• EVALUATION: plasticity doesnt always decrease with age

  • bezzola et al - 40hrs of golf training produced changes in neural representations of movement (40-60 years)
  • FMRIs - observed increased motor cortex activity in novice not control group - more efficient neural representations after training
  • neural plasticity can continue through lifespan
• EVALUATION: negative behavioural consequences

  • brain's adaptation to prolonged drug use = poor cognitive functioning in later life + risk of dementia
  • 60-80% of amputees develop phantom limb syndrome (unpleasant, painful) - cortical reorganisation of somatosensory cortex
  • brains ability to adapt to damage = not always benefical
• EVALUATION: real world application to functional recovery

  • understanding process contributed to field of neurorehab
  • understanding axonal growth encourages new therapies e.g constraint induced movement therapy for stroke patients - repeat practice of affected part of body + unaffected arm restrained
  • helps medical professionals know when intervention is necessary
• EVALUATION: level of education may influence recovery rates

  • schneider et al - more education = greater chances of disability free recovery
  • 40% of DFR clients = >16 years of education, 10% = <12 years
  • people with brain damage who have insufficient cognitive reserve = less likely to achieve full recovery